where \(\lceil x \rceil \)  denotes the smallest integer greater or equal to \(x\)  and \(t\)  is an activation value.
The second and third parallel layers, both of size \({N_{\sf {RF}} \times N_{\sf {U}}}\) , respectively generate the real and imaginary part of the DP. Finally, the fourth layer of size \({N_{\sf {RF}} \times N_{\sf {T}}}\)  is only activated for the DSA-HBF structure and designs the multiplexer network.
We considered the “Gumbel-Softmax” activation function [1]} to satisfy the constraint described in (REF ). More details will be given in Section REF  regarding this choice.
